Digital video data is typically compressed to reduce storage capacity and/or transmission bandwidth requirements. The ITU-T H.264 standard for compression/decompression of digital video signals supports Context-based Adaptive Binary Arithmetic Coding (CABAC), which is an efficient form of entropy coding that continuously adapts to the statistical properties of the data being coded. For example, CABAC coding/decoding requires only about 50% of the bit rate required by MPEG-2 coding/decoding to achieve the same general quality of video reproduction. Although relatively more efficient than the Huffman coding/decoding used in MPEG-2 coding/decoding, CABAC coding/decoding generally comprises a sequential multi-step process that is relatively more computationally intensive. As a consequence, parallel hardware architectures generally have limited utility in improving throughput in CABAC coding/decoding.
Data symbols in digital video signals are binarized, or converted into binary values, during CABAC coding. Accordingly, CABAC decoding requires conversion of the binary values back into symbols. This process is known as debinarization.
U.S. Pat. No. 6,900,748, entitled “Method and apparatus for binarization and arithmetic coding of a data value”, issued to Marpe et al. on May 31, 2005 and has been assigned to Fraunhofer-Gesellschaft zur Foerderung Der Angewandten Forschung e.V. According to this document, results from an arithmetic decoder are buffered and a debinarized value is calculated based on the result of a comparison between a codeword value and a cut-off value.
U.S. Pat. No. 6,856,701, entitled “Method and system for context-based adaptive binary arithmetic coding”, issued to Karczewicz et al. on Feb. 15, 2005 and has been assigned to Nokia Corporation. This document relates to an overall system level architecture for implementation of a CABAC algorithm.
U.S. Pat. No. 6,927,710, entitled “Context based adaptive binary arithmetic CODEC architecture for high quality video compression and decompression”, issued to Linzer et al. on Aug. 9, 2005 and has been assigned to LSI Logic Corporation. This document relates to an overall system level architecture for implementation of a CABAC algorithm.
The debinarization process is computationally intensive and has to be performed within time constraints imposed by real time video. Thus, a need exists for improved methods and apparatuses for performing debinarization that are relatively less computationally intensive and/or require relatively less data storage than existing arrangements.